Lawmakers are pressuring President Barack Obama to act on his administration's suspicion that the Syrian government has used chemical weapons, a move the president has said would cross his "red line."

"I urge President Obama to explain to Congress and the American people how he will ensure Syria's chemical and biological weapons stockpiles are secured, how we'll work with our allies to prevent further use of these deadly weapons, and what additional measures he is ready to take to follow through on his previous statement," Sen. Marco Rubio, R-FL., said in a statement Thursday.

The President first established his "red line" on Syria this summer, saying the use of chemical weapons would change his calculations significantly, but some military experts question whether he drew the line too soon.

Former Deputy Assistant Secretary of Defense and Heritage Foundation Senior Fellow Peter Brookes called the red line an "embarrassment to Obama."

"I think the Obama team has laid down a marker that's regrettable," NBC News Military Analyst Gen. Barry McCaffrey said. "It's always a mistake to put out in public your red line and imply what you'll do. It should be done in private."

McCaffrey, a retired U.S. Army General, said it would be difficult to find a sensible way to intervene in Syria.

"It would be utter nonsense to go after chemical weapons," he said. "The only option is on-the-ground power, but there is zero likelihood this will happen. It would cause uproar in the country."

Sen. John McCain, R-AZ., said the U.S. must take action in Syria but agreed that military intervention is not the next step.

"It requires the United States' help and assistance," McCain told reporters. "It does not mean boots on the ground."

House Intelligence Committee Chairman Rep. Mike Rodgers, R-MI., urged President Obama to outline a specific plan for the transition to a post-Assad Syria, saying "the world is waiting for American leadership."